The international applications WO 97/28131 (=U.S. Pat. No. 6,191,138), WO 97/35854 (=U.S. Pat. No. 6,127,378), WO 99/05113 (=U.S. Pat. No. 6,121,279), WO99/05111 (=U.S. Pat. No. 6,410,551), WO 00/42018, WO 00/42020, WO 02/05616 and WO 02/06238 describe 6-phenylphenanthridines as PDE4 inhibitors.